Greason, Kevin L.

ObjectivesTo assess technical performance learning curves of teams performing transfemoral transcatheter aortic valve replacement (TF‐TAVR).BackgroundTF‐TAVR is a new procedure for treating severe aortic stenosis. The number of cases required for procedural efficiency is unknown.MethodsIn the PARTNER‐I trial, 1,521 patients underwent TF‐TAVR from 4/2007–2/2012. Learning curve analysis of technical performance metrics was performed using institution‐specific patient sequence number, interval between procedures, and institutional trial entry date. Learning curve characteristics were assessed using semi‐parametric and parametric mixed‐effects models.ResultsAs patient sequence number increased, average procedure time decreased from 154 to 85 minutes (P < 0.0001), and fluoroscopy time from 28 to 20 minutes (P < 0.0001). Procedure time plateaued at an average of 83 minutes (range 52–140). Procedure time plateau was dynamic during the course of the trial, averaging 25 cases (range 21–52) by its end. The later institutions enrolled in the trial, the shorter the initial procedure time. During the trial, percutaneous rather than surgical access increased from 7.9% to 69%.ConclusionsTechnical performance learning curves exist for TF‐TAVR; procedural efficiency increased with experience, with concomitant decreases in radiation and contrast media exposure. The number of cases needed to achieve efficiency decreased progressively, with optimal procedural performance reached after approximately 25 cases for late‐entering institutions. Knowledge and experience accumulated by early TF‐TAVR institutions were disseminated, shortening the learning curve of late‐entering institutions. Technological advances resulting from learning during the trial moved the field from initial conservative surgical cut‐down to percutaneous access for most patients. © 2015 Wiley Periodicals, Inc.

Background— Low-flow, low-gradient aortic stenosis (AS), associated with a poor prognosis, can be caused by a reduced stroke volume despite a preserved ejection fraction (left ventricular ejection fraction). We hypothesized that impaired ventricular diastolic filling secondary to constrictive pericarditis (CP) could contribute to reduced transaortic gradients in patients with AS+CP. We sought to examine the characteristics and outcomes of this unique cohort. Methods and Results— We analyzed 84 patients with different degrees of AS and preserved left ventricular ejection fraction (≥50%): 28 diagnosed with concomitant CP by echocardiography and 56 patients without CP matched by age, sex, and AS severity during 1998 to 2013. Prior mediastinal radiation (32.1% versus 5.4%; P =0.0072) and cardiac surgery (50.0% versus 3.6%; P =0.0016) were more common in AS+CP patients than those with AS only. AS+CP patients had lower left ventricular stroke volume index and mean transaortic gradients. Five-year survival was 34.3% for AS+CP patients and 89.1% for those with AS only ( P <0.001). In univariate analysis, prior mediastinal radiation (hazard ratio, 8.35; 95% confidence interval, 3.38–20.62; P <0.001), reduced left ventricular stroke volume index of <35 mL/m 2 (hazard ratio, 12.52; 95% confidence interval, 3.97–39.48; P <0.001), and concomitant CP (hazard ratio, 13.65; 95% confidence interval, 4.85–38.41; P <0.001) were highly associated with increased mortality. Conclusions— Our findings highlighted the possibility of CP as a pathophysiological mechanism for low-flow, low-gradient AS. Left ventricular stroke volume index and transaortic gradients were commonly reduced in AS in the setting of CP despite a preserved left ventricular ejection fraction, which may result in underestimation of AS severity. Prior mediastinal radiation, lower left ventricular stroke volume index, and concomitant CP were associated with poorer survival in AS patients.